As a method of producing reduced glutathione by electrolytic reduction of oxidized glutathione, a method using an aqueous oxidized glutathione solution acidified by adding a mineral acid such as concentrated hydrochloric acid and the like to a cathode side electrolytic cell (patent document 1), a method using an aqueous oxidized glutathione solution having electrical conductivity improved by adding a conducting agent other than an acid for an electrolytic cell on the cathode side (patent document 2), and a method using an aqueous oxidized glutathione solution having a pH adjusted to higher than 3.0 and 7.0 or below by adding a base, as an electrolytic cell on the cathode side (patent document 3) are known.
However, since the methods of patent documents 1 and 2 include electrolytic reduction in an acidic region, when a metal is used as the cathode, corrosion of the metal of the cathode was unavoidable.
While patent document 3 teaches that corrosion of the metal of the cathode can be suppressed since electrolytic reduction in a neutral region is possible, complete prevention of corrosion of the metal of the cathode has not been achieved.